Published German patent specification DAS No. 21 64 058 relates to basic substituted 4-benzyl-1-(2H)-phthalazinone derivatives having the following formula: ##STR4## wherein R is a hydrogen or halogen atom, a trifluoromethyl group or a lower alkyl or alkoxy group and E is a 4-perhydroazepinyl, N-methyl-4-perhydroazepinyl, 3-quinuclidyl, 3-tropanyl, 3-nortropanyl, N-methyl-3-pyrrolidinyl or N-methyl-2-pyrrolidinyl methyl radical as well as physiologically acceptable acid addition salts hereof.
These compounds possess an antihistaminic effect.